The Zakah is due on the land prepared for sale after the passage of a full Hawl from the time when the intention for sale was determined, because it is a kind of commercial commodity. Thus, the owner should evaluate it upon the end of the Hawl and pay the due Zakah, which is 2.5% of the price of evaluation at the time when Zakah is due. This is admittedly true whether the value of the land is more or less than the price of purchase. If someone does not have enough money to pay the due Zakah in time, it will remain a debt on them until they have the means and pay it.May Allah grant us success. May Allah's Peace and Blessings be upon Prophet Muhammad and upon his family and Companions!